Chronology of Milestone Events in Particle Physics - BRABANT 1956C
Chronology of Milestone Events in Particle Physics


Brabant, J.M.; Cork, B.; Horwitz, N.; Moyer, B.J.; Murray, J.J.; Wallace, R.; Wenzel, W.A.;
Terminal Observations on Antiprotons
Phys. Rev. 101 (1956) 498;

Recently Chamberlain, Segrè, Wiegand, and Ypsilantis have observed negatively charged particles of mass 1840 90 me, emerging from a target of the Berkeley Bevatron. In their experiment, protons of 6.2 BeV energy bombarded a Cu target, and secondary particles of unit negative charge emitted near 0 were selected in a momentum orbit of 1.20 0.02 BeV/c by the system of deflecting and focusing magnets described in reference 1. Their additional measurement of flight time over a 40-ft portion of the path allowed the identification of mass within the limits mentioned above, and certain requirements of response in special Cerenkov counters assisted in rejecting background events. The fact that each of these unique particles was accompanied by about 4.4 x 104 negative pions within the defined momentum channel emphasizes the importance of background rejection.
Since it is required of an antiproton that it be capable of annihilation in combination with a nucleon, it is significant to observe the passage through matter of particles purported to be antiprotons, and particularly to examine the region of their range endings for evidences of large energy release. The first aim of the experiment described here was to show that the proton-mass particles produce events different from those associated with passage of the negative pion beam. If such observations can be made on a quantitative basis they can presumably insure the identity of these particles as antiprotons in distinction from combinations of K mesons, hyperons, or unknown objects that could demonstrate the proper charge, mass, and lifetime. Annihilation is expected to occur in several modes, but the immediate products may include pions, photons, and possibly K mesons; and the identities and multiplicities of these product particles may vary. (Extracted from the introductory part of the paper.).

Accelerator LBL Detectors CNTR

  nucleus mult[charged] X p
  nucleon annihil p

Particles studied

Record comments
Confirmation of the existence of the antiproton.
  New Comments List of Comments NY